[VOL-3860] redis client support in voltha-lib-go

redis client support has been added in this patch. There are two
types client `redis` and `redis-sentinel` to connect a redis instance.
redis-sentinel is required to be able to find the master redis
instance from a redis-sentinel process. See redis-sentinel usage
https://redis.io/topics/sentinel and
https://pkg.go.dev/github.com/go-redis/redis/v8#NewFailoverClient
for more information. If there is no need to have any failover
mechanism then the redis client type is the option to choose.

Change-Id: I997ed92115a9d565df632c6dd8184b9bab77b991
diff --git a/vendor/github.com/go-redis/redis/v8/Makefile b/vendor/github.com/go-redis/redis/v8/Makefile
new file mode 100644
index 0000000..49e4c96
--- /dev/null
+++ b/vendor/github.com/go-redis/redis/v8/Makefile
@@ -0,0 +1,21 @@
+all: testdeps
+	go test ./...
+	go test ./... -short -race
+	go test ./... -run=NONE -bench=. -benchmem
+	env GOOS=linux GOARCH=386 go test ./...
+	go vet
+	golangci-lint run
+
+testdeps: testdata/redis/src/redis-server
+
+bench: testdeps
+	go test ./... -test.run=NONE -test.bench=. -test.benchmem
+
+.PHONY: all test testdeps bench
+
+testdata/redis:
+	mkdir -p $@
+	wget -qO- http://download.redis.io/redis-stable.tar.gz | tar xvz --strip-components=1 -C $@
+
+testdata/redis/src/redis-server: testdata/redis
+	cd $< && make all